The present invention relates to the field of industrial plants for the production of paints, varnishes, enamels, inks and the like, and in particular to a system for handling containers in those plants.
Known types of industrial plant for the production of paints and varnishes usually comprise lines for handling the paint containers which are carried in sequence to processing stations including, for example, stations for filling, for metering and delivering dyes, for mixing, for weighing and checking, and also for packing, storing and/or despatching.
An example of an industrial plant of the type indicated above is described in the document EP-A-0 427 497 which illustrates a conventional container-handling system which comprises tracks having idle and/or motor-driven rollers which transport the containers along predetermined paths. Other transport and handling systems normally used also in other technological fields involve the use of endless and motor-driven conveyor belts, the upper face of which supports the containers which are to be transported from one station of the plant to another.
Another example of a transport system is disclosed in document U.S. Pat. No. 4,151,907 which shows a walking beam conveyor having a cam (32) at only one of its end driving a longitudinally extending beam (26). First and second linkage means (48, 54) move the beam transversely, e.g. vertically, and longitudinally, e.g. horizontally, of the conveyor.
The prior art transport systems have a number of disadvantages, above all the low degree of precision in reaching accurate positions along the production line, which means that it is necessary to adopt often expensive arrangements for ensuring the correct placement of the containers, for example, beneath the delivery nozzles of the dye-dispensing machines. It should be borne in mind that containers for paints and varnishes often have a very small opening on the upper face which is closed with a cap once the container has been filled. The small dimensions of that opening, together with the necessity to deliver correctly often very small amounts of dye to the inside of the container, make it necessary to provide means suitable for ensuring the exact centring of the hole below the delivery nozzle. Given the poor positioning precision of the transport systems of known type, in conventional plants it is necessary to provide a series of additional means at the individual work stations, such as guides, stops, mechanical manipulators, robots, and the like. This naturally involves a complication of the plant both in mechanical terms and in control terms, with a consequent reduction in the reliability, repeatability and quality of production during the prolonged and intensive use for which such plants are intended.
A further disadvantage of the known systems is the inability to manage multi-form production, that is to say, in which the containers have different shapes and dimensions.
Another disadvantage of the transport systems of the prior art, especially for use in plants for the production of paints and varnishes, is the difficulty of keeping such systems clean, above all if a dye product, a varnish or a paint is spilt or upset on them, which could spoil the containers themselves and therefore impair the quality and appearance of the final packaging of the product.
The object of the present invention is to overcome the disadvantages of the prior art by providing a system for transporting and handling containers which is precise and reliable and which is at the same time economical and simple to produce.
In order to achieve that object, the present invention relates to a system for transporting containers, which is especially suitable for use in a plant for the production of paints, varnishes and the like, characterised in that it comprises a longitudinally extending bearing structure for containers, comprising a first, fixed, portion defining one or more fixed coplanar bearing surfaces, and a second, movable, portion defining one or more movable coplanar bearing surfaces, handling means being connected operatively to the movable portion in order, in use, to bring about coordinated movements of lifting/lowering and longitudinal advance/return of the movable portion relative to the fixed portion.
A particular advantage of the present invention is afforded by the fact that the handling system can be provided in modular form, with segments of predetermined length which can be readily assembled to form portions of transporter of the desired length.
A further advantage of the present invention is provided by the fact that it is readily possible to clean the transport system owing to the substantially planar form of the transport surfaces.
Another advantage of the present invention is that it is possible to predetermine with precision not only the positioning of each individual container along the production line but also the relative distance between one container and another, so as to ensure a correct time sequence in the operation of the individual machines in each work station without having to resort to the extensive and generalised use of presence-sensing means at each work station, which clearly has favourable results as regards the overall economy of the plant, its reliability, and the simplicity of managing the complete production process, especially with the large production volumes for which the plants of the type indicated above are intended.
Yet another advantage of the present invention is provided by the quiet operation of the transport system compared with the prior art systems, owing to the fact that the impacts between the containers and the bearing surfaces are substantially reduced and the risk of contact between the various containers, which remain spaced from one another by a predetermined distance over the entire handling path, are also completely eliminated, thus also reducing the risk of the containers being damaged, in particular dented.
A further advantage of the present invention is provided by the fact that it is also possible to transport and handle simultaneously containers having widely varying dimensions, without having to make any modification to the structure or to the components of the transport system, and while still ensuring optimum precision of advance and positioning along the path of the plant.
A further advantage resides in the fact that it is also possible to produce long transport path segments operated by a single motor, simply by combining and connecting small modular portions which can be readily stored and transported.
Naturally, although the invention has been developed with particular regard to a plant for the production of paints, varnishes and the like, the transport and handling system to which the invention relates could also be used in other technological fields which require just as accurate a system for positioning parts or members within the framework of a production line.